Endless-belt conveyors



May 29, 1956 s. D. ROBINS 2,747,726

ENDLESS-BELT CONVEYORS Filed July 5, 1952 8 Sheets-Sheet l llllINVENTOR. SAMUEL DA v/s Ros/N5 A 770R NE Y5 May 29, 1956 s. D. ROBINSENDLESS-BELT CONVEYORS 8 Sheets-Sheet 2 Filed July 3, 1952 May 29, 1956s. D. ROBINS ENDLESS-BELT CONVEYORS 8 Sheets-Sheet 3 Filed July 5, 1952INK BT01? SAMUEL 0/2 v15 Foam/s S. D. ROBINS ENDLESS-BELT CONVEYORS May29, 1956 8 Sheets-Sheet 4 Filed July 3, 1952 8 KM 0 o 71/ E WW. Q\ V \lo 0 m w 0 w m M w \\w m v g A: g. =3 8 n w L L w L g TTORNEY? May 29,1956 s. D. ROBINS ENDLESS-BELT CONVEYORS 8 Sheets-Sheet 5 Filed July 3,1952 E R5 mm 00m N 0 mm T .N W/T IA 0 A L E a W a W/ V: B

'l'lll I I IIII IIOIII Ill- y 1956 s. D. ROBINS 2,747,726

ENDLESS-BELT CONVEYORS Filed July 5, 1952 8 Sheets-Sheet 6 a! INVENTOR.

5AMUL DAV/5 Ros/N3 /l TTOENEYS.

May 29, 1956 s. D. ROBlNS ENDLESS-BELT CONVEYORS 8 Shuts-Sheet 7 FiledJuly 3, 1952 5 Mo n N Z mw D g H U a M A u 5 m 9 TTOR/VEYS y 1956 s. D.ROBINS 2,747,726

ENDLESS-BELT CONVEYORS Filed July 3, 1952 8 Sheets-Sheet 8 INVENTOR.

- 5AMUL DAV/5 Ra /Ms A TTO/E'NEYS United States Patent ENDLESS-BELTCONVEYORS Samuel Davis Robins, Lawrence, N. Y.

Application July 3, 1952, Serial No. 297,064

6 Claims. (Cl. 198-203) This invention relates to endless-belt conveyoror elevator systems of utility for transporting minerals or othermaterials over long distances, horizontal or inclined, and it relatesmore particularly to such systems in which an endless moving cradle beltis wholly supported both in its upper run and its lower run by wheels orrollers which run upon tracks and is combined with an endless movingpropelling cable or cables, together with means for connecting anddisconnecting the belt and cable or cables, so that the belt may becable driven.

It is among the objects of this invention to enable a positive powerfulfrictional connection of the belt to the cable or cables to be made thatwill be proof against slippage even at such severe angles as 30 to thehorizontal at which the belt may be inclined in its path of travel; tomultiply the useful life of the cable many times and as much as ten oreven more times beyond that which has heretofore been consideredpossible for cables in beltconveyor usage; and, to enable a continuousconveyor belt to be operated when desired around curves in plan equallyas well as in elevation, without having to terminate the belt at anypoint intermediate the starting and ending stations of the belt. Thelatter is a novel and very valuable feature heretofore unknown ofaccomplishment in any belt-conveyor and one serving to eliminate thesevere wear attendant upon such operation when attempted heretofore.

These and other objects of this invention are accomplished, in partthrough the provision of certain new and useful improvements in theconstruction and arrangement of the belt, its cradles, the cable andtracks of such systems, and in part through the provision of certain newand useful weight-actuated tong means. for connecting and disconnectingthe belt and cable possessing a basic mechanical advantage and atwo-direction gripping action enabling the belt to support the cable orcables and yet be driven thereby both in itsupper arm and its lower run,whose grip upon the cable in either case is a tune-- tion of the basicmechanical advantage it possesses and is in proportion to the loadingof. the belt, and that may easily engage and as easily disengage thecable without damage to the cable, slippage or jamming.

In accordance with this invention the belt conveyor system comprises inits broad aspects three major components, namely, a track-bornecradle-belt assembly, tracks with supporting structure, and a drivecable or cables each with its associated drive machines and takeupsheave.

Thetrack-borne cradle-belt assembly as embodied is an integral assemblyof an untensionedendless belt fixedly secured to the required number ofarticulated tong-forming cradles of this invention disposed at suitableintervals along the belt. I

The drive cable asembodied comprises a bare endless wire rope. A singlerope is ordinarily preferred, but two or more may be used if desired. Itis made endless by a long splice as in conventional ropeways, tramways,or power transmission systems. There are no attachments 2,747,726Patented May 29,

of any kind to the rope, such as are found on mono ca ble tramways.Therefore, the more efiicient types of drive may be used, high initialtensioning being unnecessary. Everything about the rope, its drives,sheaves, etc., follows established good engineering custom. The rope atno time has to engage a sheave tangentially but on the contrary takes atleast a quarter wrap on sheaves. It is supported throughout the run ofthe conveyor by the cradle-belt assembly. It is not subject tocontamination or wear ad should have at least a 10-year life.

The tracks, as embodied, are firmly supported through the length of theconveyor as by stringers of the track supporting structure, and mayconsist merely of fiat bars. The track supporting structure, asembodied, is of whatever structural arrangement and type is best suitedfor the locale in and conditions under which it is to be used. It mayrest on the ground, act as a truss to bridge short spans, or besuspended by cables to cross great spans.

The articulated tong-forming cradles possess certain salient and novelfeatures as regards both design and functions. Thus, the ease with whichthe cradle belt assembly can engage and disengage the drive cable, orthe facility of the cradle belt assembly to travel around the terminalpulleys, arises from the concept of the articulated cradle with itscable'engaging tongs.

The cradle structure in accordance with this invention may be singly ordoubly articulated. in its singly articulated form each cradle half maycomprise an angle bar, a wheel and axle assembly, a tong, and a clampplate. The tong and clamp plate are below the belt being bolted to theangle bar which is above the belt. Thus, the belt is sandwiched betweenthe parts of the assembled cradle; The wheel and axle assembly issecured to the outer end of the unit.

In order that the several functional requirements of the articulatedcradle structure may be fully understood, it should be noted that atroughed belt cannot be reversed on itself at the terminals withoutflattening itself where it wraps the pulley. Hence, one reason forhaving the cradle of articulate form. Another reason exists forarticulation of the cradle, namely, to permit engaging the drive cableand holding it tightly enough to ensure no slip. With the articulatedcradle in accordance with this invention, when the cable is engaged, thecradle becomes a rigid beam, but when the cable is disengaged, thecradle is unlocked and free to articulate, that is, go into a flatposition for rounding terminals, and return to a troughed section forthe straightaway top and bottom runs.

The cradle serves as a moving support for the belt and its load on thecarrying run and for the empty belt on its return run. Moreover, inaccordance with this-invention, the cradle serves not only to supportthe drive cable throughout both runs but to grip the cable withsufiicient pressure to secure slip-free traction from the cable.

The tractive pull is highest where the belt is on the steepest incline,and added tractive pull must be exerted in starting where accelerationis added to the weight load plus the friction load. I i

In accordance with this invention, the distance from a tong hinge orfulcrum of the cradle to the cable may be referred to as the tong leverarm, and the distance between this point and either rail of the tracksystem may be referred to as the load lever arm. The shorter the tonglever arm and the longer the load lever arm, the higher the grippingforce between the tong jaws and the cable. Advantageously, a tong leverarm of about one twentysixth of the track gauge may be used. This givesanv loaded belt causes a tighter bite than the empty belt. Thus, thetractive force required is a direct function of the basic mechanicaladvantage offered by the tong lever arm-weight lever arm ratio, and isin proportion to the loading of the belt.

In accordance with one embodiment of this invention, the tong jaws,which for convenience may be designated as right-hand and left-handjaws, have each a right-hand lobe and a left-hand lobe formingtherebetween a socket for the cable enabling a two-direction action.Thus, in the right-side-up or load-carrying position of the cradles, thejaws lock the drive cable in shear with the cable bearing against theleft lobe of the right-hand jaw and the right lobe of the left-hand jaw.But when the cradle is inverted, gravity still acting down, the shearload is reversed, and the opposite lobes bear on the cable.

Means are provided for releasing or disengaging the connection betweenthe belt and cable at certain points in the circuit, and rc-engaging atothers. Release points are upstream of head, tail or intermediate drivestations, while rte-engagement points lie downstream of said stations.In order not to chafe or wear either the faces of the tong jaws or thedrive cable itself, it is of the utmost importance that engagement ordisengagement, whichever the case may be, be smooth and deliberate.Advantageously, the releasing means may be in the form of a separate setof gently rising rails or rollers, or a gently rising endless belt unit,acting upwardly on the central portion of I the cradle to relieve theload on the tong jaws and gradually spread them apart to an openposition. Then, but not till then, the cradle wheels encounter acorresponding gentle rise in the track serving with the rails to liftthe open jaws clear of the cable. As the cradle and the drive rope arealways traveling at the same speed, the release, if performed asoutlined, occurs with no scuifing or other deleterious effect either onthe tong jaws or the cable. In the inverted position of the cradle, therelease may be effected by the same form of releasing means, or thewheels may be pushed or crowded together to raise the central portion ofthe cradle thereby to release the grip on the cable. The same principlesapply to engagement, but in the reverse manner, and the same applies atall stations whether head, tail, or intermediate drive stations.

Thus, as the loaded belt approaches a selected station in its upper run,it disengages, rises with the tongs clear of the drive cable, lowers ashort distance beyond the station, and reengages the cable. If the trackat the drive station is curved in plan, the belt, being free of thecable, is also free to traverse the curve without interference from thecable and, if desired, the cable may be led around suitable pulleys toand through booster drive located externally of the track and thenceback to the track structure. On the return run at the same station, thebelt disengages, lowers with the tongs clear of the drive cable, rises ashort distance beyond the station and reengages the cable. Here also thecable is free to be led around pulleys outside the track.

In the accompanying drawings which form part of the instantspecification, and are to be read in conjunction therewith, and in whichlike numbers refer to like parts throughout the several views:

Fig. 1 is a fragmentary view in side elevation at the driving end(discharge end) of a preferred embodiment of endless-belt conveyorsystem in accordance with this invention, certain of the parts beingbroken away in order to show more clearly the construction andarrangements of other parts;

Fig. 2 is a view in plan of the embodiment shown in Fig. 1;

Fig. 3 is a view in section taken along the line 3-3 of Fig. 1, andshowing details of upper and lower track'- borne articulatedtong-forming cradle structures each with its tongs in driving engagementwith the cable of the systern;

Fig. 4 is a part sectional view in plan taken along the line 4-4 of Fig.3 and showing the manner in which the cradle tongs grip the cable on itsreturn run;

Fig. 5 is a part sectional view in elevation taken along the line 55 ofFig. l and showing the flattened condition of the cradle structures intransport around the tail pulleys;

Fig. 6 is a part sectional view in elevation taken along the line 6-6 ofFig. l and showing a cradle structure of the upper run in the last stageof its cable disengaging run, and showing a cradle structure of thelower run in the initial stage of its cable engaging run;

Figs. 7 and 7a are broken diagrammatic views in elevation which takentogether show a complete endless cablebelt conveyor system in accordancewith this invention but omitting the cable system for clarity ofshowing, the system embodying a horizontally curved section in Fig. 7and a vertically curved section in Fig. 7a in each of which thearticulated cradle belt assembly is disengaged from the drive cable andcaused to follow a curved path;

Figs. 8 and 8a are broken diagrammatic views in elevation of the cablesystem of the unit shown in Figs. 7 and 7a, the view showing theintermediate drive systems for the cable in the horizontally curvedsection, Fig. 8, and in the vertically curved section, Fig. 8a;

Figs. 9 and 9a are broken diagrammatic views in plan of the cable systemof Figs. 8 and 8a, respectively;

Fig. 10 is a view in vertical section through a modified form of endlesscable-belt conveyor system in accordance with this invention, thesection plane corresponding generally to that of Fig. 3 and the viewshowing a double cable system in which a pair of double articulatedcradle structures are in a cable-engaging position in their upper andlower runs, respectively;

Fig. 11 is a fragmentary view in plan with parts in section taken alongthe line 1111 of Fig. 10;

Fig. 12 is a fragmentary view in section taken along the line 1212 ofFig. 10;

Fig. 13 is a view in vertical section of the modification shown in Fig.10, the section plane corresponding generally to that of Fig. 6 to showthe cradle structures in a cable disengaged position corresponding tothat of the cradle structures of Fig. 6;

Fig. 14 is a view in vertical section of the modification shown in Fig.10, the section plane corresponding generally to that of Fig. 5 to showthe cradle structures of the upper and lower runs, respectively, inflattened condition in transport around the tail pulleys of the beltsystem;

Fig. 15 is a view in vertical section of another form of endlesscable-belt conveyor system in accordance with this invention, thesection plane corresponding generally to that of Fig. 3 and the viewshowing a double tong cradle structure for use with a single cablesystem having horizontally offset upper and lower cradle runs,respectively;

Fig. 16 is a fragmentary view in plan taken along the line 1616 of Fig.15; and,

Fig. 17 is a fragmentary view in elevation taken along the line 1717 ofFig. 15.

Referring now more particularly to Figs. 1 to 9 inclusive of theaccompanying drawings, upper and lower suitably vertically spaced tracks1 and 2, respectively, are supported at suitable intervals by a suitableframework comprising vertical posts 3, horizontal stringers 4 andlongitudinal stringers 5. The tracks 1 and 2 extend over whateverdistance is desired between a pair of coaxial spaced head pulleys 6 atone end and a corresponding pair of tail pulleys 7 at the other. Thetracks may be straightaway and horizontal, or inclined, or includecurved sections either horizontally or vertically curved as required bythe terrain. As here preferably embodied, the tracks comprisestraightaway sections S1 and S2 connected by a horizontally curvedsection H as is best seen by the diagrammatic showing of Fig. 7, and avertically curved section V connecting the straightaway section S2 withan inclined section I, as is best seen in Fig. 7a. The curved sectionsas shown each constitute an intermediate drive station as will morefully appear hereinafter, although as many additional intermediate drivestations may be employed as are necessary having regard to the length ofthe conveyor system.

An endless conveyor belt 8 runs between and over the head and tailpulleys 6 and 7, respectively, to provide upper and lower runs 811 and8L respectively, and may be suitably initially lightly tensioned as bycounterweight means 9 connected to and operating on the tail pulleyshaft 10 in known manner. The diameter of the head and tail pulleys andthe spacing of the upper and lower tracks is suitably coordinated toplace the upper run 8a of the belt above the upper track 1 and the lowerrun ill of the belt below the lower track 2.

An endless drive cable 11 extends between and over a tail pulley 12, ahead pulley 13, and suitably disposed upper and lower sets of tail idlerpulleys l-tu and 141, head idler pulleys 15a and 151 and intermediatedrive idler pulleys 16M and 161 to provide upper and lower cable runs11a and 111. The cable runs are vertically aligned midway between therails of the tracks 1 and 2 except at booster or intermediate drivestations such as those in the curved sections H and V whereat the cableruns llu and 111 are diverted laterally outside the track, by the idlerpulley sets 16M and 161, respectively, as best appears in Figs. 9 and9a.

The tail pulley 12 and the head pulley 13 for the cable are eachpreferably located outside the track supporting structure. The headpulley 13 is journalled in bearing supports 17 and 18. The tail pulleyshaft 19 is suitably adjustably mounted to permit tensioning of thecable as by the counterweight means 19 connected to and operating on thepulley shaft 19 in known manner.

The intermediate or booster drive for the cable 11 at each of the curvedtrack sections H and V preferably comprises a pair of annularly groovedcable drums 2t) and 21 located wholly outside the track supportingstructure and journalled for rotation on parallel axes. The cable drum2t} is power-driven as by an electric motor 22 acting through a suitablereduction gearing 23. The upper run 111: of the cable 11 is guided ontoand off of the drums and 21, respectively, by means of the upper set ofidler pulleys 1611 in a manner which will be clearly apparent from Figs.8, 8a, 9 and 9a. The cable makes several half wraps, advantageously fiveor more, around each drum. Thus, the necessary tractive effort isimparted to the upper run of the cable at the upstream side of the drum29. On the downstream side of the drum 21, the tension in the upper runis only that imparted to it by the succeeding downstream boosterstation, or head drive. The lower run 11[ of the cable is led out of andback into its normal running position centrally of the track by the.lower set of idler pulleys 161 so as to run around and completely clearthe booster or intermediate drive station.

Articulated cradle structures 24 spaced at suitable intervals along theendless belt 8 form therewith an inseparable cradle-belt assembly. Thecradle structures 24 are identical and. each structure is symmetrical,both halves being identical. In accordance with the illustrativeembodiment thereof depicted in Figs. 39 inclusive, each half comprisesupper and lower beam members 25 and 26, respectively, between which thebelt 8 is sandwiched. Advantageously the beam member 26 may be a flatplate, and the beam member 25 may be an angle iron, as shown. They aresecured. together so as to clamp the belt 8 therebetween, as by means ofrivets 27, bolts, or other suitable securing means passing therethrough.

A wheel and axle assembly comprised of a flanged wheel 28 is attached toeach cradle half at the outer end of the beam member 26 for rollingengagement of the wheel 28 with the rails of the upper track 1 in theoutward movement of the belt toward the head pulley, and

for rolling engagement with the rails of the lower track 2 on the returnrun of the belt.

A tong member 29 attached to each cradle half at the inner end of thebeam member 26 comprises a tong jaw 30 and a cam follower member 31, bywhich opening and closing of the tong jaw is effected. The tong jaws 30have their pivotal connection 32 with each other in the vertical planeof symmetry of the cradle structure 24, in which plane the axis of theupper and lower runs 11a and Ill, respectively, of the cable 11 alsolies. The tong pivot 32 is vertically spaced from the cable 11 above thecable in the upper run, and below the cable in the lower run, as clearlyappears in Fig. 3.

Each tong jaw 30 is preferably provided also with a pair ofcable-engaging lobes 33 and 34 providing therebetween a recess 35 forreceiving the drive cable 11. Each jaw is also provided with a stop lug36 serving to limit the extent of angular movement of the jaws 30 to adetermined amount in either direction, as will more fully appearhereinafter.

The camfollower members 31 as here preferably embodied each comprise aroller 37 having an arcuate surface and adapted to ride upon a tongcamming rail 38 for the purpose of opening or closing the tong jaws inengaging, or disengaging, the tongs with or from the cable in its upperrun at the head, tail and intermediate drive stations of the conveyorsystem.

The tong-camming rails 33 are disposed in pairs at the required stationsalong the conveyor, one at each side of the cable 11 in its upper run,as best appears in Figs. 2 and 6. The rails of each pair are suitablysupported on and in parallel relation to each other, as by longitudinalstringers 39 (Fig. 6) secured to the horizontal stringers 4.

Each of the tong camming rails 38 is of a configuration to provide,intermediate its ends, an inclined surface portion 40 upon which theroller 37 of a given cam follower member is adapted to ride and beraised or lowered, as the case may be. For the purpose of opening thetongs in the upper run, a given pair of the rails 38 is disposed so thatthe inclined surface portion 40 of each will present an upwardlyinclined surface to the advancing roller and thus raise it, or viceversa. Advantageously, each tong camming rail 38 terminates at each endof its inclined portion 40 in a straightaway portion 41 serving to guidethe roller into and out of the inclined camming portion of the rail.

As will be apparent from Fig. 3, the cradle structures 24 in their upperrun are supported in a troughed condition by the wheels 28 upon therails of the upper trackl wherein the weight of the cradle-beltassembly, plus its load, acts downwardly. Because the cradle isarticulated at the pivot 32', this downward load functions to cause thetongs 30 to grip the drive cable 11 tightly, and the cradle constitutesa track-borne rigid beam supporing both the load and the-cable. Thegreater the loading, the greater the gripping action of the tongs on thecable.

In accordance with this invention however, the 'grip of the tongues onthe cable in its upper run may be released at any convenient point inorder to permit the cradles to be entirely freed from the cable. Thecradles when thus freed may be caused to assume a flattened conditionfor passage around the head and tail pulleys, or to enable the cradlesin a troughed state to follow freely a curvature in the track whetherthe curvature be in the vertical or horizontal plane. Moreover, byfreeing the cradle structures from the cable at selected points it ispossible to lead the cable outside the track suporting structure at thehead and tail of the conveyor and at intermediate drive stations forrelieving the stress in the cable at such stations and to make itpossible to employ successfully and in a commercially feasible manner,an endless belt of light weight'and low cost covering many miles ofterrain. To this end therefore, the tracks 1 and 2 are provided withramps 42 for elevating or lowering the tongs 30 as may be required,between opposite extremes of position in one of which the cable lieswholly outside the tong socket 35 and in the other of which the cable isseated in the tong socket. In the illustrative embodiment of thisinvention as depicted in Figs. 7 and 7a, the ramps 42 are disposed atthe head and tail stations, respectively, and at the entrance and exitof the intermediate drive stations H and V at which, in the illustratedembodiment, the track is curved.

The ramps 42 in the upper track 1 are positionally coordinated with thecamming rails 38 so that the action of the latter either precedes orfollows the action of the former. In order that the coordinated actionof the ramps and camming rails on a given cradle in transit on the uppertrack may be clear, reference may be had to Figs. 1, 3, 5, 6 and 7a inparticular. In Fig. 7a, particularly with reference to the uncouplingramp 42 of the track 1 located just ahead of the head pulley 6, it willbe noted that the camming rail 38 is disposed so that its inclinedportion 40 precedes the upwardly inclined ramp 42. Thus, as a givencradle moves toward the pulley 6 on the level portion of the track 1preceding the inclined portion 40 of the camming rail 38, the tongs 30firmly grip the cable 11 in the position shown in Fig. 3. In thisposition the cable 11 is wholly contained in the sockets 35 of the tongjaws and is gripped between the left-hand lobe 33 of the right-hand tongjaw and the right-hand lobe 33 of the left-hand tong jaw, as seen inFig. 3. The force with which the tong jaws grip the cable is a functionof the loading of the belt and the basic mechanical advantage offered bythe articulated cradle and its cable-gripping tongs. As the cradleadvances, the camming rollers 37 meet the inclined portion 40 of thecamming rails 38. As the rollers travel up the incline, the cradlehalves are fulcrumed on the rails of the track to raise the pivot point32, thus articulating the cradle halves on the pivot point and releasingthe grip of the tong jaws on the cable. Then and only then, the wheels28 of the advancing cradle meet the uncoupling ramps 42. As the cradlemoves up the ramp, the tongs 30 are gradually lifted clear of andpreferably above the cable as to the position shown in Fig. 6. The track1 may continue on for a short distance at its new level beyond the ramp,as desired.

As the cradle continues its forward movement toward the axially-spacedhead pulleys 6, the articulation of the cradle permits it to flattenuntil at the head pulleys 6 it is in a fully flattened position as shownin Fig. 5, to round the pulleys. The latter are suitably spaced axiallyto receive therebetween the tong structure of the cradle throughout itstravel on the head pulleys.

Upon completing its travel on the head pulleys, the cradle is in aninverted but still flattened position as appears in Fig. 5. In thisposition, the stop lug 36 on each tong jaw abuts firmly against the bodyportion 43 of its companion tong jaw to prevent troughing of the cradlestructure and thus serves to maintain the cradle structure in itsflattened condition as it leaves the underside of the head pulleys 6.

Means are provided for troughing the cradle upwardly as it commences itsreturn run so that the tong may be positioned properly for reengagementwith the drive cable in its lower or return run. The embodied means isdisposed in the vertical plane of symmetry of the cradles between thehead pulleys 6 and the beginning of the return track 2, and is adaptedto maintain the pivot connection 32 of the belt at substantially thepitch line level of the head pulley at which the belt leaves the headpulleys, while leaving the cradle halves free to articulate downwardlyby their own weight on the pivot connection 32 until they attain theinverted troughed position in which the recesses 35 in the tong jaws arealigned ready for coupling to the return run 111 of the cable, asindicated in Fig. 6. When this position has been attained, the wheels 28of the advancing inverted cradle meet the rails of the lower track 2,and coupling of the cradle to the cable may proceed. As here preferablyembodied, the

troughing means comprises a series of rollers 44 between the pulleys 6and the track 2, each supported on a suitable structural member 45 atthe same elevation and in the plane of symmetry of the cradles at thehead pulley end. The top of each roller is at a level correspondingsubstantially to the tangent to the pitch line of the pulleys 6 at thepoint of departure of the belt therefrom.

Each cradle 24 on attaining the desired inverted position shown in Fig.6 enters upon the track 2 (see Fig. 1) which is preferably provided withan approach section 46 for a short distance to maintain the wheels 28 atthe same elevation preparatory to the cradle being coupled by the tongs30 to the return run 111 of the cable. The gauge of the track 2 over theapproach section 46 is selected to maintain the tongs 30 in their opencable-receiving position shown in Fig, 6. The flanged wheels 28 makethis possible since the cradle in its inverted position tends to flattenout under its own weight. This is resisted by the rails of the track 2bearing against the wheel flanges.

The coupling ramp 42 at the end of the approach section 46 serves toraise each cradle until the lower run 111 of the cable is seated in thealigned cable recesses 35. The gauge of the track 2 then graduallywidens as shown in Fig. 6, until at the top of the ramp the normalrunning gauge is reached. During this interval, the tong jaws 30 of thecradle are caused by the weight of the cradle to grip the cable tightlytherebetween in the condition shown in Fig. 3. From then on, until thecradle is to be uncoupled from the cable, the cradle is track-borne andtowed by the cable which it supports.

When uncoupling of the cradle is necessary as, for example, at theintermediate drive station of the vertically curved track section V,Fig. 7a, the downwardly inclined uncoupling ramp 42 at the entrance tothis section is gauged first to squeeze the wheels 28 together so as torelease the grip of the tong jaws on the cable and place them in aposition to be lowered freely away from the cable, and then to lower thecradle down the incline until the jaws lie completely below the cable.The recoupling ramp 42 at the end of the section V functions preciselyin the manner of the coupling ramp at the beginning of the return track2. Moreover, it will be apparent that the coupling and uncoupling of thecradles 24 and lower cable run 111 at any desired station along thereturn run follows the principles outlined above.

In accordance with this invention also, the coupling and uncouplingramps 42 of the upper and lower tracks are arranged in pairs so that thecoupling and uncoupling operations on the respective tracks will occursubstantially simultaneously. This is of particular importance at thebeginning and end of a curved section of the track or at anyintermediate drive station.

It will be apparent from the foregoing that through the medium of thisinvention, the drive cable 11 may be led to the sides of the trackstructure at any desired location and, by the use of an intermediatedrive, the cable tension maintained within permissive limits. Moreover,since the cradle construction is such that the cable engaging jaws liebeneath the cradle, it is possible for the cradle-belt assembly to beendless over whatever distance is desired, and for the drive cable to beendless also and located between the upper and lower runs of the endlessbelt where it may be diverted laterally to booster stations as required.

In the embodiment of this invention shown in Figs. l0-14 inclusive,there is depicted a double articulated troughed cradle structure for usewith dual cable flights in both its upper and lower runs under heavyduty conditions where the loads are heavy, the inclines steep, or thelike. The cable 11 is endless as in the previous case but is suitablyreeved as by the use of oppositely inclined drive and tail pulleys inknown manner, to provide parallel flights of cable in both upper andlower runs. The cradle, symmetrical about its center line, comprises thecombination with the endless belt 8 of an upper beam member 47 and alower beam structure between which the belt 8 is clamped. The lower beamstructure as here preferably embodied comprises a camming member 48carrying at its opposite ends a pair of camming roller 49, the member 48being secured to the upper beam member 47 as by bolts 50. The lower beamstructure further comprises at each end of the camming member 48, a tongmember 51 also bolted or otherwise suitably secured to the upper beammember 47 and having pivotally connected thereto by a pivot pin 53, awheel-carrying tong member 52. Each tong member is preferably channelshaped for strength and is of a configuration to provide, as to each, apair of parallel tong jaws each having inner and outer lobes 54 and 55,respectively, providing aligned cable recesses 56. As in the case of thesingly articulated cradle, the cable 11 when seated in the recesses 56is clamped during its upper run between the inner tong jaw lobes 54 ofthe tong member 52 and the outer tong jaw lobes 55 of the tong member51. The arrangement however provides greater gripping area on the cable.The clamping is in the opposite direction however during the lower runof the cable, as is shown in Fig. 10.

The tong member 51 is provided with a shelf portion 57 upon which troughportions 58 of the belt are supported when the cradle is in itsflattened condition for passage around a head or tail pulley 59 as shownin Fig. 14.

Each tong member 52 is of a configuration to support or hold therespective trough portions 58 of the belt at a suitable angle in boththe upper and lower runs of the belt and to this end is provided with anextended surface portion 60 slidably engaging the under surface of therespective trough portions. Thus, as the tong member 52 is caused topivot on the pin 53, the trough portion 58 in engagement therewith isfreely movable with respect thereto.

Each tong member 52 carries a wheel 61 which the cradle may be supportedby, and travel on, the tracks 1 and 2. A stop lug 62 is suitably locatedon each tong member 62 through which it passes from side to side, toengage the shelf portion 57 of the tong member 51 at one extreme ofangular movement, and engage the tong jaw lobes 55 of the same member atthe other extreme.

It will be apparent that the weight of the cradle acting down on thetong pivot pins 53 will cause the tong jaws to come together both in theupright position and the inverted position of the cradle structure inFig. 13. By suitably locating camming rails 63 (Fig. 13) to coact withthe camming rollers 49 after the manner described for the singlyarticulated cradle, the engaging and disengaging of the cable by thetongs may be readily effected, as will be apparent to those skilled inthe art. Likewise, through the employment of coupling and uncouplingramps as previously described, the cradle may be raised from or loweredonto the cable flights in its upper run to effect the desired couplingand uncoupling at head, tail and intermediate drive stations. Thus, thefreed cable flights may be diverted outwardly to booster stations, orhead and tail pulleys, as required.

In Figs. 15-17 inclusive, there is depicted a modified form of singlearticulated cradle structure 24 adapted for use in a conveyor system inaccordance with this invention in which the endless cable 11 has itsupper and lower runs horizontally offset at equal distances to the leftand right respectively of the plane of symmetry of the cradle, as shownin Fig. 15.

The cradle tong means as here preferably embodied is or arecharacterized by a pair of tong members 29, one having a doubled lobedtong jaw 30 comprising spaced pairs of lobes 64 and 65 spaced apart adistance sufiicient to span the cable 11 both in its upper and its lowerruns.

The other tong member 29 has-its tong jaw 30 provided with a single pairof lobes 66 extending therefrom a distance sufiicient to form separatecable recesses 67 with the lobes 64 and 65 respectively. Thus,articulation of the cradle halves on the tong pivot 32 enables the tongsto grip the cable 11 between the lobes 66 and 64 in its upper 10 run andbetween the lobes 66 and 65 in its lower run. In either case, thegripping action is a direct function of the loading of the belt 8 andthe basic mechanical advantage of the track-borne articulatedcradle-belt assembly.

Articulation of the cradle to effect coupling and uncoupling of thetongs may be effected as described for the embodiment of Figs. 1-9, andto this end the tong lobe 64 carries a camming roller 68 which may alsofunction as a troughing roller in co-action with the troughing rail 69.Likewise, a stop pin 70 carried by the tong lobes 65 is adapted toco-act with abutments 71 on the other tong member to limit the angularmovement of the cradle halves between a flattened condition in transportover head and tail pulleys and a condition of maximum troughing duringcoupling and uncoupling of cradle and cable.

The cradle 24 is supported as shown upon the tracks 1 and 2. In order toeifect improved tracking of the cradlebelt assembly, particularly overtrack sections curved in azimuth, the assembly may comprise anarticulated wheel assembly 72, advantageously embodying double-flangedor sheave-type wheels arranged in tandem fore and aft of a verticalspindle. In such case, the rails of the tracks 1 and 2 and the wheelsmay be of a configuration in crosssection adapting them to nesting witheach other so as to minimize derailing. Such a construction is embodiedin the assembly of Fig. 15 wherein tandem wheels 73 are mounted on atruck 74 journalled by a vertical spindle 75 to a mounting plate 76secured to the cradle structure extremities. Thus, relative pivotalmovement between the wheel trucks 74 and the mounting plate 76 mayfollow as the cradle-belt assembly traverses curves. Moreover, by theuse of tandem wheels, a lower load intensity and more effective loaddistribution with lessened track wear, is attainable.

It will be noted that in the tong designs thus far described, the hingeaxis is close to the belt but not so close but that a local distortionof the belt occurs as a result of cradle articulation. In narrow belts,24" wide and under, this distortion is not objectionable but where Widebelts, say 60", are used, the proportionate belt thickness leads toexcessive distortion unless the pin axis is practically coincident withthe neutral axis of the belt structure. Advantageously, such an idealhinge location may be obtained by cutting a rectangular hole in the beltto provide space for the hinge and, if desired, for passage of the tonghalves therethrough for attachment to the top of the belt. Moreover, insuch a design, the hinge itself may be dispensed with and the tonghalves permitted to abut at the hinge point in rocker fashion. The easyflexing of the belt thus obtained outweighs the disadvantage of havingto punch a hole in the belt. In this form the gravity loading of theupper run leads to a compressive abutment of the tong halves while onthe lower run with the cradle inverted the gravity loading tends to pullthem apart, which tensile load is taken in the belt itself.

The invention in its broader aspects is not limited to the specificmechanisms shown and described, but departures may be made therefromwithin the scope of the accompanying claims without departing from theprinciples of the invention and without sacrificing its chiefadvantages.

What is claimed is:

1. A belt-conveyor system for transporting material over long distances,horizontal or inclined, comprising upper and lower tracks; an endlessdrive cable; a cradlebelt assembly comprising an endless belt andwheeled cradle structures mounted at spaced intervals on said belt forsupporting said belt in its upper and lower runs in rolling engagementwith said upper and lower tracks, respectively, said cradle structureseach being articulated and comprising each at least a pair of rigid beammembers disposed cross-wise of said belt and secured thereto inend-to-end relationship to each other, each of said pair of beam membershaving means forming a tong jaw at its contiguous end, the tong jaws ofsaid beam members together providing a weight-actuated tong forconnecting 1 l the cradle structure to said cable at certain points inthe belt circuit and disconnecting it at others, each said tong whenconnected to said cable having its hinge axis located between said cableand said belt and having its jaws constructed and arranged to grip saidcable in its upper and lower runs, respectively, between different pairsof gripping surfaces; means for raising and lowering the hinge axis ofsaid cradle structures for releasing the connection between said cradlestructures and said cable at certain points in the belt circuit, andreengaging at others; and, means for raising and lowering said cradlestructures toward and away from said cable in its upper and lower runswhen disconnected from said cable.

2. A belt-conveyor system for transporting material over long distances,horizontal or inclined, comprising upper and lower tracks; an endlessdrive cable; a cradlebelt assembly comprising an endless belt andwheeled cradle structures mounted at spaced intervals on said belt forsupporting said belt in its upper and lower runs in rolling engagementwith said upper and lower tracks, respectively, said cradle structurescomprising at least two sections disposed in line with one anothertransversely of the belt and affixed thereto and being articulated forhinging movement in opposite directions from a flattened condition inwhich they are adapted for passage over head and tail pulleys of thesystem to upright and inverted troughed positions in the upper and lowerruns, respectively, of the belt, said cradle structures comprisingtong-forming means providing weight-actuated tongs for connecting saidcradle structures to said cable, each said tong having its hinge axisclosely adjacent said belt and between said belt and said cable whenconnected thereto and having its jaws constructed and arranged to gripsaid cable in its upper and lower runs, respectively, between differentpairs of gripping surfaces; and, camming means for initially elevatingsaid cradle structures substantially centrally thereof at selectedstations in the circuit of said belt to open said tongs, whereby saidcradle structures may be thereafter disengaged from said cable at saidstations.

3. A belt-conveyor system in accordance with claim 2 in which saidcradle structures additionally comprise cam follower members to beactuated by said camming means for centrally elevating said cradlestructures and in which said camming means comprise rail membersdisposed at said stations and having inclined camming surface portionsfor engaging said cam follower members at said stations.

4. A belt-conveyor system in accordance with claim 2 in which saidstations are located both in the upper run and in the lower run of thebelt.

5. A belt-conveyor system in accordance with claim 3 in which said railmembers disposed at stations in the upper run of the belt areindependent of said upper track and in which said rail members disposedat stations in the lower run of said belt are a part of said lowertrack.

6. In a belt-conveyor system having head and tail pulleys, an endlessbelt carried by said pulleys providing an upper carrying run and a lowerreturn run therebetween, an endless drive cable for said belt, and upperand lower tracks disposed lengthwise on said belt: the combination withsaid belt of a plurality of belt-supporting cradles for said belt, eachsaid cradle comprising at least two rigid belt-supporting sectionsdisposed end-to-end in line with one another transversely of the belt,each said section being fixedly secured to said belt; wheels carried byeach said cradle at its outer extremities, said wheels being adapted torun on said lengthwise disposed tracks; lugs carried by said sections attheir inner extremities and hingedly interconnecting the sections at alocus closely adjacent to the belt but between said belt and said drivecable for hinging movement of said sections in opposite directions froma flattened condition in which said sections are adapted for passageover the head and tail pulleys of the system to upright and invertedtroughed positions in the upper and lower runs, respectively, of thebelt, said lugs projecting downward beneath the carrying run of saidbelt to form at the juncture of said sections a pair of two-directionalgrippers for pinchingly engaging said driving cable both in the uppercarrying run of the belt and in its lower return run, said gripperspinching the cable in the upper carrying run of the belt in proportionto the load moment developed in the span between the tracks, and, in theinverted position of the cradle on the return run the cable is likewisegripped, the load moment being reversed, whereby the belt is driven ateach cradle by the cable.

References Cited in the file of this patent UNITED STATES PATENTS2,609,086 McBride et al Sept. 2, 1952 FOREIGN PATENTS 495,420 GermanyApr. 7, 1930 502,639 Germany Oct. 31, 1930

